Dr Colin Walker from the Melbourne Bird Clinic reports: On May 1 the PMV vaccine trial birds were again taken to the Melbourne Bird Veterinary Clinic. Blood was collected from all birds and forwarded to the lab for a PMV HI score. The average flock titre was 4. However two birds now have a reading of 2. Bearing in mind that a reading of 3 is required to be protective this means that these two birds ie: 10% of the group would be vulnerable to PMV if exposed.